The present invention relates to a radio-resource management system and a method thereof, a management apparatus, a base station and a terminal to be employed for it, and a program thereof, and more particularly to a technique of managing a radio resource extending over networks of a plurality of radio operators in a wireless network such as public mobile communication by a cellular technique, and a wireless LAN.
In a conventional wireless network, each radio operator installed radio base stations independently, and the radio resource such as a frequency channel that the radio base station and a radio terminal utilize, transmitted power of a radio link, and a transfer rate was managed independently operator by operator. In the event of the public mobile communication by the cellular technique, an exclusive right to the use of a frequency band is normally given to each operator as license, whereby no radio interference occurs between the operators, and the management of the radio resource is in a good state because it is independently managed enterprise by enterprise. In the event of assuming such an exclusive form of the radio resource by the license, the radio-resource management to be made by the radio operator becomes easy in the degree to which the interference from the other radio operator does not need to be considered.
In this case, however, even though a traffic demand is remarkably less than forecasted in a network of a specific radio operator, and there exists the radio resource excessively, it is impossible to accommodate the other radio operator with its excess, whereby the problem exists that availability efficiency of the frequency goes down.
On the other hand, in the event of a wireless LAN system employing a frequency band such as 2.4 GHz and 5 GHz that does not necessitate the license, not only networks of a plurality of the radio operators and private networks, but also the system other than the wireless LAN utilizing the same frequency band hold the radio resource in common. In the event of the wireless LAN, conventionally, each radio system was isolated in many cases, and there were few cases where intra-radio-system physical interference occurred between the operators because the maximum transmitted power was restricted at a relatively low level. Also, in operating the wireless LAN within an enterprise, also in the event that the wireless LAN areas overlap, to autonomously control the terminal or the radio base station alone sufficed for a radio-resource management method because it was relatively easy to realize unification of a management policy.
For example, as a method of the terminal's selecting the radio base station autonomously in the wireless LAN, there is a method in which, responding to a radio-link quality that the terminal measured, a load of the wireless LAN, and so forth, the terminal selects the radio base station for connection, of which the condition is best suitable for it (see patent documents 1 and 2).
Also, as an autonomous radio-resource management technique by the radio base station in the wireless LAN, there is a method of dynamically switching over an operational frequency channel of the wireless LAN responding to noise and interference (see patent document 3). Furthermore, as a technique of cooperatively managing the radio resource by the terminal and the radio base station, there is a method in which the radio base station stores statistic information of the link quality for respective radio terminals, and comes up with the other radio base stations that become a candidate for a migration destination in the order of priority (see patent document 4).
[Patent Document 1]
JP-P2001-298467A (pages 6 and 7, FIG. 6)
[Patent Document 2]
JP-P2001-274816A (pages 7 and 8, FIG. 4)
[Patent Document 3]
JP-P2002-009664A (page 2, FIG. 1 and FIG. 2)
[Patent Document 4]
JP-P2001-103531A (pages 2 to 5, FIG. 1 to FIG. 4)
These kinds of the autonomous radio-resource management by the terminal or the radio base station are relatively easy of realization, whereas the problem exists that they do not always function as originally planned because there is restriction to information that can be mutually notified between the wireless networks of the plural operators having different operational policies, and also, because the effect can be expected only when almost all terminals and radio base stations correspond to the autonomous radio-resource management.
In particular, the operator that provides an internet connection service by the wireless LAN in a public space such as an airport, an assembly fall, and a restaurant has rapidly increased in recent years, and from now on, the situation is expected where the service areas of the plural operators overlap inside the identical public space. In this case, a plurality of the radio operators mutually hold the radio resource in common, and as a result, the interference of the radio occurs between the systems. In the conventional autonomous radio-resource management technique, each radio operator is to alter the frequency channel of the radio base station, the transmitted power, the position of the radio base station, etc. so as to avoid the interference based on limited information that it can utilize; however optimal radio-resource allocation is not always made in the entire system having the plural operators brought together because information is limited. Also, in the event that a load was concentrated on a specific operator, such a scheme of distributing it among the operators did not exist. Also, in such a manner, a scheme of managing the radio resource of the plural operators in an integrated manner did not exist, whereby the service responding hereto was also not considered.